STMicroelectronics

ST1S12GR - 3A, 18V Synchronous Step-Down Regulator | STMicroelectronics

Name: ST1S12GR
Brand: STMicroelectronics
Price: 1.25 USD
Availability: InStock

MPN: ST1S12GR ✓ Active

In Stock (99,999) Ships in 1-3 business days

0.8 V to VIN Vdss 3 A Id SOT-23-6 (TSOT-6) Package 1.5 MHz Speed

$1.25 USD / Unit

MOQ: 1 |

Volume Pricing

Qty	Unit Price	Extended
1	$1.25	$1.25
10	$1.12	$11.20
100	$0.98	$98.00
500	$0.85	$425.00
1,000	$0.75	$750.00

ℹ️ All prices are in USD

View Datasheet (PDF) View Alternatives

Quantity

Drop-in alternatives for ST1S12GR — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.

Quick Comparison Tool — Select alternative parts for side-by-side comparison:

ST1S12GR

✅ Drop-In

STMicroelectronics

📦 SOT-23-6

Adjustable · 0.8 V to VIN · 3 A · 4.5 V to 18 V · 1.5 MHz · Up to 95% · Yes · Current Mode

✓ 99,999 In Stock

$0.75 / Unit

View Datasheet →

ST1S12G

✅ Drop-In

📦 SOT-23-6

Same die, different package variant (SOT-23-5)

📋 Reference alternative (not in catalog)

TPS54331DR

✅ Drop-In

📦 SOT-23-6

Cross-brand, wider input range (3.5-28V), lower switching frequency (570kHz)

📋 Reference alternative (not in catalog)

MP2307

✅ Drop-In

📦 SOT-23-6

Cross-brand, 3A, 4.75-23V input, 340kHz switching

📋 Reference alternative (not in catalog)

RT8059

✅ Drop-In

📦 SOT-23-6

Cross-brand, 3A, 4.5-23V input, 1.5MHz switching

📋 Reference alternative (not in catalog)

ST1S12GR Maximum Ratings & Electrical Characteristics

Output Type	Adjustable
Output Voltage Range	0.8 V to VIN
Maximum Output Current	3 A
Input Voltage Range	4.5 V to 18 V
Switching Frequency	1.5 MHz
Efficiency	Up to 95%
Synchronous Rectification	Yes
Control Architecture	Current Mode
Soft Start	Internal
Overcurrent Protection	Yes
Thermal Shutdown	Yes
Operating Temperature	-40C to +150C
Package	SOT-23-6 (TSOT-6)
Mounting Type	Surface Mount
RoHS Status	Compliant

ST1S12GR Pin Configuration

Pin 1	SW — Switch node output
Pin 2	GND — Ground
Pin 3	FB — Feedback input
Pin 4	EN — Enable input
Pin 5	IN — Input supply
Pin 6	GND — Ground (exposed pad)

Safe Operating Area (SOA) & Thermal Characteristics

No official SOA curve available for this component. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.

Typical Applications

ST1S12GR is suitable for 6 applications: Point-of-Load (POL) Converters, Set-Top Boxes and Networking Equipment, Industrial Control Systems, Battery-Powered Devices, FPGA and DSP Power Supplies, Automotive Infotainment.

⚡

Point-of-Load (POL) Converters

The ST1S12GR is ideal for POL converters powering FPGAs, DSPs, and microcontrollers. Its 3A output current and adjustable voltage from 0.8V to VIN allow it to supply core and I/O rails. The 1.5MHz switching frequency enables small inductors and capacitors, saving board space. In a typical POL design, the ST1S12GR is placed close to the load, with input and output capacitors to minimize parasitic inductance. The high efficiency reduces heat dissipation, improving system reliability. Compared to linear regulators, the buck converter offers higher efficiency, especially at higher input-to-output voltage differences.

Recommended

STM32F407 (Microcontroller requiring 3.3V core supply) EP4CE6 (FPGA requiring multiple voltage rails)

🌐

Set-Top Boxes and Networking Equipment

The ST1S12GR provides a regulated 3.3V or 5V rail from a 12V input in set-top boxes and networking equipment. Its wide input range (4.5V to 18V) accommodates various power supplies. The synchronous rectification ensures high efficiency, reducing heat and improving reliability in enclosed spaces. The compact SOT-23-6 package fits into dense PCB layouts. In a set-top box, the ST1S12GR can power the main SoC, memory, and interface ICs. The 1.5MHz switching frequency minimizes EMI, which is critical for consumer electronics. The internal soft-start prevents inrush current during power-up, protecting the input supply.

Recommended

BCM7230 (Set-top box SoC requiring 3.3V rail) AR8035 (Ethernet PHY requiring 1.8V rail)

🏭

Industrial Control Systems

The ST1S12GR is suitable for industrial control systems that operate from 24V buses. Its input range up to 18V covers 12V and 24V systems with proper derating. The high efficiency reduces thermal stress in industrial enclosures. The device's overcurrent and thermal protection ensure robust operation in harsh environments. In a PLC, the ST1S12GR can generate a 5V rail for logic circuits and a 3.3V rail for microcontrollers. The current-mode control provides fast transient response, essential for motor control and actuator loads. The wide operating temperature range (-40C to +150C) meets industrial requirements.

Recommended

STM32F103 (Microcontroller for industrial control) ISO1050 (CAN transceiver requiring 5V rail)

📱

Battery-Powered Devices

The ST1S12GR is ideal for battery-powered devices where efficiency is critical. Its synchronous architecture achieves up to 95% efficiency, extending battery life. The 100% duty cycle operation allows the output to track the input voltage as the battery discharges, maximizing usable capacity. The low quiescent current in light-load conditions further improves efficiency. In a portable device, the ST1S12GR can step down a 2-cell Li-ion battery (6-8.4V) to a 3.3V rail for the main processor. The small package and high switching frequency reduce the solution size, fitting into compact designs. The internal soft-start prevents battery voltage dips during startup.

Recommended

STM32L4 (Low-power microcontroller) BQ24075 (Battery charger)

🖥️

FPGA and DSP Power Supplies

The ST1S12GR provides core and I/O voltages for FPGAs and DSPs, which often require multiple rails with tight voltage tolerances. The adjustable output and 3A current capability make it suitable for powering high-current cores. The fast transient response of current-mode control ensures stable operation during dynamic load changes. In an FPGA design, the ST1S12GR can generate a 1.0V core rail and a 3.3V I/O rail. The high switching frequency allows the use of small ceramic capacitors, reducing board space. The device's efficiency reduces heat, which is critical in high-density designs. The enable pin (if available) allows power sequencing.

Recommended

XC7A35T (FPGA requiring 1.0V core) TMS320F28379D (DSP requiring 3.3V rail)

🚗

Automotive Infotainment

The ST1S12GR is suitable for automotive infotainment systems that operate from a 12V battery. Its input range up to 18V handles load dump transients. The device's thermal shutdown and overcurrent protection ensure reliability in automotive environments. The high efficiency reduces heat in the dashboard. In an infotainment system, the ST1S12GR can power the main processor, display, and audio amplifier. The 1.5MHz switching frequency minimizes EMI, which is important for EMC compliance. The compact package fits into space-constrained head units. The wide operating temperature range meets automotive requirements.

Recommended

i.MX6 (Application processor) TDA7802 (Audio amplifier)

Recommended Products Summary

STM32F407 Microcontroller requiring 3.3V core supply Used in: Point-of-Load (POL) Converters EP4CE6 FPGA requiring multiple voltage rails Used in: Point-of-Load (POL) Converters BCM7230 Set-top box SoC requiring 3.3V rail Used in: Set-Top Boxes and Networking Equipment AR8035 Ethernet PHY requiring 1.8V rail Used in: Set-Top Boxes and Networking Equipment STM32F103 Microcontroller for industrial control Used in: Industrial Control Systems ISO1050 CAN transceiver requiring 5V rail Used in: Industrial Control Systems STM32L4 Low-power microcontroller Used in: Battery-Powered Devices BQ24075 Battery charger Used in: Battery-Powered Devices XC7A35T FPGA requiring 1.0V core Used in: FPGA and DSP Power Supplies TMS320F28379D DSP requiring 3.3V rail Used in: FPGA and DSP Power Supplies i.MX6 Application processor Used in: Automotive Infotainment TDA7802 Audio amplifier Used in: Automotive Infotainment

What is the input voltage range of ST1S12GR?

The ST1S12GR operates with an input voltage range of 4.5V to 18V. According to the STMicroelectronics datasheet, this wide range makes it suitable for 5V, 12V, and 24V bus systems.

What is the maximum output current of ST1S12GR?

The ST1S12GR can deliver up to 3A of continuous output current. This makes it suitable for powering FPGAs, DSPs, and other high-current loads.

What is the switching frequency of ST1S12GR?

The ST1S12GR operates at a fixed switching frequency of 1.5MHz. This high frequency allows the use of small inductors and capacitors, reducing the overall solution footprint.

Is ST1S12GR a synchronous buck converter?

Yes, the ST1S12GR is a synchronous step-down converter with integrated high-side and low-side MOSFETs. This improves efficiency by reducing conduction losses compared to non-synchronous designs.

What is the output voltage range of ST1S12GR?

The ST1S12GR has an adjustable output voltage range from 0.8V to VIN. The output voltage is set by an external resistor divider.

What is the efficiency of ST1S12GR?

The ST1S12GR achieves up to 95% efficiency at light loads. Efficiency varies with input/output voltage and load current, but the synchronous architecture ensures high efficiency across a wide range.

Does ST1S12GR have overcurrent protection?

Yes, the ST1S12GR includes overcurrent protection to safeguard the device and the load from excessive current. It also features thermal shutdown for additional protection.

What package is ST1S12GR available in?

The ST1S12GR is available in a SOT-23-6 package, also known as TSOT-6. This compact package is suitable for space-constrained applications.

What is the operating temperature range of ST1S12GR?

The ST1S12GR operates over a junction temperature range of -40C to +150C. This wide range makes it suitable for industrial and automotive environments.

Where can I buy ST1S12GR online?

ST1S12GR is available from major distributors such as DigiKey and Mouser. As of 2026-08-07, the price for 1 unit is approximately $1.25 USD.

What is the lead time for ST1S12GR?

The lead time for ST1S12GR varies by distributor and stock availability. Typically, it ranges from 1 to 4 weeks. Check with DigiKey or Mouser for current stock and lead times.

ST1S12GR vs TPS54331 - which is better for a 3.3V output?

For a 3.3V output, the ST1S12GR offers a higher switching frequency (1.5MHz vs 570kHz) and a smaller SOT-23-6 package, making it more compact. The TPS54331 has a wider input range (3.5V to 28V) and higher output current (3A), but the ST1S12GR is more efficient at light loads. Choose ST1S12GR for compact designs, TPS54331 for wider input range.

When should I choose ST1S12GR over TPS54331?

Choose ST1S12GR when you need a compact, high-frequency solution with high efficiency at light loads, such as in battery-powered devices. Choose TPS54331 if you require a wider input voltage range (up to 28V) or need to handle higher transient currents.

What is the best drop-in replacement for ST1S12GR?

The best drop-in replacement for ST1S12GR is the TPS54331DR from Texas Instruments, which shares the same SOT-23-6 package and pinout. However, verify the pinout and parameters before production use, as the TPS54331 has a lower switching frequency.

Where can I download the ST1S12GR datasheet PDF?

The ST1S12GR datasheet PDF can be downloaded from the STMicroelectronics website at https://www.st.com/resource/en/datasheet/st1s12.pdf. It contains detailed specifications, pinout, and application circuits.

What are the key specifications of ST1S12GR that engineers should know?

The ST1S12GR is a 3A synchronous step-down converter with an input range of 4.5V to 18V, adjustable output from 0.8V to VIN, and a fixed 1.5MHz switching frequency. It features current-mode control, internal soft-start, overcurrent protection, and thermal shutdown, all in a SOT-23-6 package.

Hey Google, what can replace ST1S12GR?

The ST1S12GR can be replaced by the TPS54331DR from Texas Instruments, which is pin-compatible and shares the same SOT-23-6 package. Other alternatives include the MP2307 from MPS and the RT8059 from Richtek, but verify pin compatibility.

Is ST1S12GR the same as TPS54331?

No, the ST1S12GR and TPS54331 are not the same. They are from different manufacturers (STMicroelectronics vs Texas Instruments) and have different specifications, such as switching frequency (1.5MHz vs 570kHz) and input voltage range (4.5-18V vs 3.5-28V). However, they are pin-compatible in the SOT-23-6 package.

What is the best Texas Instruments equivalent for ST1S12GR?

The best Texas Instruments equivalent for ST1S12GR is the TPS54331DR, which is a 3A synchronous buck converter in the same SOT-23-6 package. It has a wider input range but a lower switching frequency, so verify performance for your application.

Engineering reference data for ST1S12GR — comparison, design guidance, and compliance information.

Selection Guide

Choose the ST1S12GR when you need a compact, high-frequency synchronous buck converter with high efficiency at light loads, such as in battery-powered devices or space-constrained POL designs. If you require a wider input voltage range (up to 28V), consider the TPS54331DR, but note its lower switching frequency. For cost-sensitive applications, the MP2307 offers a lower price but with reduced efficiency and switching frequency. The RT8059 is a close equivalent with similar specifications and is a good drop-in alternative. All alternatives share the SOT-23-6 package, but verify pinout and parameters before production use.

Comparison with Alternatives

Parameter	This Product	ST1S12G	TPS54331DR	MP2307	RT8059
Package	SOT-23-6	SOT-23-5	SOT-23-6	SOT-23-6	SOT-23-6
Brand	STMicroelectronics	STMicroelectronics	Texas Instruments	Monolithic Power Systems	Richtek
Input Voltage Range	4.5V to 18V	4.5V to 18V	3.5V to 28V	4.75V to 23V	4.5V to 23V
Output Current	3A	3A	3A	3A	3A
Switching Frequency	1.5MHz	1.5MHz	570kHz	340kHz	1.5MHz
Synchronous Rectification	Yes	Yes	Yes	Yes	Yes
Control Architecture	Current Mode	Current Mode	Current Mode	Current Mode	Current Mode
Efficiency	Up to 95%	Up to 95%	Up to 92%	Up to 90%	Up to 95%

Key Differentiators

Higher switching frequency (1.5MHz) enables smaller external components (vs TPS54331DR)
Higher efficiency at light loads (vs MP2307)
Same-brand package variant available (vs ST1S12G)

Design Notes

Place the input capacitor (10uF ceramic) as close as possible to the IN pin to minimize parasitic inductance. Use a solid ground plane and connect the exposed pad to the ground plane with multiple vias for thermal dissipation. Keep the feedback trace short and away from the SW node to avoid noise coupling.

The ST1S12GR in SOT-23-6 has a thermal resistance of approximately 90C/W (theta_JA). At 3A output with a 12V to 3.3V conversion, power dissipation is about 1.5W, resulting in a 135C temperature rise. Ensure adequate copper area and airflow to keep the junction temperature below 125C for reliable operation.

Do not exceed the absolute maximum input voltage of 20V. Use an inductor with a saturation current rating higher than the peak current (typically 1.2x the maximum output current). The feedback resistor divider should use 1% tolerance resistors to maintain output voltage accuracy. Ensure the EN pin is not left floating; tie it to VIN if not used.